Incidence of chronic immune-mediated inflammatory diseases after diagnosis with Kawasaki disease: a population-based cohort study.

OBJECTIVES: Kawasaki disease (KD) is an immune-mediated vasculitis of childhood with multi-organ inflammation. We determined the risk of subsequent immune-mediated inflammatory disease (IMID), including arthritis, type 1 diabetes, IBD, autoimmune liver disease, primary sclerosing cholangitis and multiple sclerosis. METHODS: We conducted a matched population-based cohort study using health administrative data from Ontario, Canada. Children aged <18 years born between 1991 and 2016 diagnosed with KD (n = 3753) were matched to 5 non-KD controls from the general population (n = 18 749). We determined the incidence of IMIDs after resolution of KD. Three- and 12-month washout periods were used to exclude KD-related symptoms. RESULTS: There was an elevated risk of arthritis in KD patients compared with non-KD controls, starting 3 months after index date [103.0 vs 12.7 per 100 000 person-years (PYs); incidence rate ratio 8.07 (95% CI 4.95, 13.2); hazard ratio 8.08 (95% CI 4.95, 13.2), resulting in the overall incidence of IMIDs being elevated in KD patients (175.1 vs 68.0 per 100 000 PYs; incidence rate ratio 2.58 (95% CI 1.93, 3.43); hazard ratio 2.58, 95% CI 1.94, 3.43]. However, there was no increased risk for diabetes, IBD, autoimmune liver disease, primary sclerosing cholangitis or multiple sclerosis in KD patients. Similar results were observed using a 12-month washout period. CONCLUSION: Children diagnosed with KD were at increased risk of arthritis following the acute KD event, but not other IMIDs. Health-care providers should monitor for arthritis in children following a diagnosis of KD.

The impact of COVID-19 on community antibiotic use in Canada: an ecological study.

OBJECTIVES: The COVID-19 pandemic has had an effect on the incidence of infectious diseases and medical care. This study aimed to describe the impact of the COVID-19 pandemic on community-level antibiotic use. METHODS: Using national antibiotic dispensing data from IQVIA's CompuScript database, this ecological study investigated antibiotic dispensing through community retail pharmacies in Canada from November 2014 to October 2020. Analyses were stratified by age, sex, prescription origin and approximate indication. RESULTS: Adjusting for seasonality, the national rate of antibiotic dispensing in Canada decreased by 26.5% (50.4 to 37.0 average prescriptions per 1000 inhabitants) during the first 8 months of the Canadian COVID-19 period (March to October 2020), compared with the pre-COVID-19 period. Prescribing rates in children ≤18 years decreased from 43.7 to 12.2 prescriptions per 1000 inhabitants in males (-72%) and from 46.8 to 14.9 prescriptions per 1000 inhabitants in females (-68%) in April 2020. Rates in adults ≥65 decreased from 74.9 to 48.8 prescriptions per 1000 inhabitants in males (-35%) and from 91.7 to 61.3 prescriptions per 1000 inhabitants in females (-33%) in May 2020. Antibiotic prescriptions from family physicians experienced a greater decrease than from surgeons and infectious disease physicians. Prescribing rates for antibiotics for respiratory indications decreased by 56% in May 2020 (29.2 to 12.8 prescriptions per 1000 inhabitants), compared with prescribing rates for urinary tract infections (9.4 to 7.8 prescriptions per 1000 inhabitants; -17%) and skin and soft tissue infections (6.4 to 5.2 prescriptions per 1000 inhabitants; -19%). DISCUSSION: The first 8 months of the COVID-19 pandemic reduced community antibiotic dispensing by 26.5% in Canada, compared with the marginal decrease of 3% in antibiotic consumption between 2015 and 2019. Further research is needed to understand the implications and long-term effects of the observed reductions on antibiotic use on antibiotic resistance in Canada.

Risk of Mental Health Problems in Children and Youths Following Concussion.

IMPORTANCE: Concussion may exacerbate existing mental health issues. Little evidence exists on whether concussion is associated with the onset of new psychopathologies or long-term mental health problems. OBJECTIVE: To investigate associations between concussion and risk of subsequent mental health issues, psychiatric hospitalizations, self-harm, or suicides. DESIGN, SETTING, AND PARTICIPANTS: This population-based retrospective cohort study including children and youths aged 5 to 18 years with a concussion or orthopedic injury incurred between April 1, 2010, and March 31, 2020, in Ontario, Canada. Participants had no previous mental health visit in the year before the index event for cohort entry and no prior concussion or traumatic brain injury 5 years before the index visit. Data were collected from provincewide health administrative databases. Participants with concussion were included in the exposed cohort, and those with an orthopedic injury were included in the comparison cohort; these groups were matched 1:2, respectively, on age and sex. EXPOSURES: Concussion or orthopedic injury. MAIN OUTCOMES AND MEASURES: The primary outcome was mental health problems, such as psychopathologies and psychiatric disorders, identified from health care visits in emergency departments, hospitalizations, or primary care settings. Secondary outcomes were psychiatric hospitalizations, self-harm health care visits, and death by suicide (identified in health care or vital statistics databases). RESULTS: A total of 152 321 children and youths with concussion (median [IQR] age, 13 [10-16] years; 86 423 [56.7%] male) and 296 482 children and youths with orthopedic injury (median [IQR] age, 13 [10-16] years; 171 563 [57.9%] male) were matched by age and sex. The incidence rates of any mental health problem were 11 141 per 100 000 person-years (exposed group) and 7960 per 100 000 person-years (unexposed group); with a difference of 3181 (95% CI, 3073-3291) per 100 000 person-years. The exposed group had an increased risk of developing a mental health issue (adjusted hazard ratio [aHR], 1.39; 95% CI, 1.37-1.40), self-harm (aHR, 1.49; 95% CI, 1.42-1.56), and psychiatric hospitalization (aHR, 1.47; 95% CI, 1.41-1.53) after a concussion. There was no statistically significant difference in death by suicide between exposed and unexposed groups (HR, 1.54; 95% CI, 0.90-2.61). CONCLUSIONS AND RELEVANCE: Among children and youths aged 5 to 18 years, concussion was associated with an increased risk of mental health issues, psychiatric hospitalization, and self-harm compared with children and youths with an orthopedic injury.

Health care costs of hospitalization of young children for respiratory syncytial virus infections: a population-based matched cohort study.

BACKGROUND: Respiratory syncytial virus (RSV) infection poses a substantial clinical burden among infants and young children. We sought to determine the health care costs of hospitalizations attributable to RSV in Ontario, Canada, from the health care payer perspective. METHODS: For this population-based matched cohort study, we identified children younger than 24 months who were or were not hospitalized with RSV infections in 2006-2016. We performed a cost-of-illness analysis using linked administrative health data, with subjects stratified by gestational age and congenital heart disease, and propensity score-matched on established risk factors. The primary outcome was attributable health care costs per patient, reflecting the difference in direct medical costs between the groups, calculated to 12 months postdischarge in 2020 Canadian dollars. RESULTS: We identified 14 608 RSV-infected children, matched to 72 040 controls. The adjusted attributable cost of hospitalized RSV was $134 931 900 over 10 years, or $9240 per patient (95% confidence interval [CI] $8790-$9690). Health care costs escalated 3 days before hospitalization, and persisted up to 12 months after discharge. Increased costs were associated with major comorbidities, but not extreme premature birth. The highest mean attributable cost per patient was in the presence of hemodynamically significant heart disease ($60 110, 95% CI $26 700-$93 060). Infants born at 36-43 weeks' gestation constituted the greatest overall cost burden at $117 886 720. INTERPRETATION: Although the greatest direct medical costs per patient hospitalized with RSV infection are among children with cardiac disease, the greatest overall cost burden is from children born at or near term, who are not targeted by current prophylaxis strategies. The substantial attributable health care costs of RSV can inform cost-effectiveness analyses of novel RSV vaccines and prioritization of health care resources.

Predictors of Hospitalization for Children With Croup, a Population-Based Cohort Study.

OBJECTIVES: We sought to determine predictors of hospitalization for children presenting with croup to emergency departments (EDs), as well as predictors of repeat ED presentation and of hospital readmissions within 18 months of index admission. We also aimed to develop a practical tool to predict hospitalization risk upon ED presentation. METHODS: Multiple deterministically linked health administrative data sets from Ontario, Canada, were used to conduct this population-based cohort study between April 1, 2006 and March 31, 2017. Children born between April 1, 2006, and March 31, 2011, were eligible if they had 1 ED visit with a croup diagnosis. Multivariable logistic regression was used to determine factors associated with hospitalization, subsequent ED visits, and subsequent croup hospitalizations. A multivariable prediction tool and associated scoring system were created to predict hospitalization risk within 7 days of ED presentation. RESULTS: Overall, 1811 (3.3%) of the 54 981 eligible children who presented to an Ontario ED were hospitalized. Significant hospitalization predictors included age, sex, Canadian Triage and Acuity Scale score, gestational age at birth, and newborn distress. Younger patients and boys were more likely to revisit the ED for croup. Our multivariable prediction tool could forecast hospitalization up to a 32% probability for a given patient. CONCLUSIONS: This study is the first population-based study in which predictors of hospitalization for croup based on demographic and historical factors are identified. Our prediction tool emphasized the importance of symptom severity on ED presentation but will require refinement before clinical implementation.

Generational Patterns of Asthma Incidence among Immigrants to Canada over Two Decades. A Population-based Cohort Study.

RATIONALE: Canada, an industrialized country with high endemic asthma rates, is characterized by a large immigrant population. OBJECTIVES: We sought to provide insight into the relative contribution of environmental exposure to asthma risk by comparing asthma rates among recent immigrants relative to long-term residents of Canada. METHODS: This was a population-based, retrospective cohort study performed using provincial health administrative data for all residents of Ontario, Canada. Residents with and without a diagnosis of asthma from fiscal years 1996-2012 were included. Individuals were categorized as being immigrants (landed in Canada after 1985) or long-term residents of Ontario by linkage with the Immigration, Refugees, and Citizenship Canada's Permanent Resident Database. We calculated the age- and sex-standardized incidence of asthma among residents of Ontario, and compared the incidence of asthma among immigrants and long-term residents using incidence rate ratios (IRRs). RESULTS: Analysis of approximately 11.7 million records showed that 2.2 immigrants arrived in Canada during the study period, with over 50% from East and South Asia and the Pacific. We found that asthma incidence was lower among immigrants compared with long-term residents (IRR = 0.30; 95% confidence interval = 0.30-0.30; P < 0.001). However, Ontario-born children of immigrants from most world regions had significantly higher asthma incidence compared with children of long-term residents (IRR = 1.44; 95% confidence interval = 1.43-1.45; P < 0.001). The overall incidence of asthma in Ontario decreased between 1996 and 2012 (Ptrend < 0.001). Immigrants contributed to only a small proportion of the asthma incidence in Ontario, and changes within this group did not significantly affect trends in the overall Ontario population asthma incidence. CONCLUSIONS: The higher asthma incidence seen among children of immigrants, but not in their parents, suggests that being born in Canada was critical for determining asthma risk. These findings support the importance of in utero and/or early life exposures on asthma development.